Carbon allotropes

ABSTRACT

A nanoparticle or agglomerate which contains connected multi-walled spherical fullerenes coated in layers of graphite. In different embodiments, the nanoparticles and agglomerates have different combinations of: a high mass fraction compared to other carbon allotropes present, a low concentration of defects, a low concentration of elemental impurities, a high Brunauer, Emmett and Teller (BET) specific surface area, and/or a high electrical conductivity. Methods are provided to produce the nanoparticles and agglomerates at a high production rate without using catalysts.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application and claimspriority to U.S. patent application Ser. No. 16/164,077 filed Oct. 18,2018, which is a continuation of U.S. patent application Ser. No.15/794,965 filed Oct. 26, 2017, which is a continuation of U.S. patentapplication Ser. No. 15/594,032 filed May 12, 2017, which is acontinuation-in-part of U.S. patent application Ser. No. 15/470,450filed Mar. 27, 2017, all of which are assigned to the assignee hereof.The disclosures of all prior applications are incorporated by referencein this patent application.

BACKGROUND

Various crude or refined hydrocarbons (e.g., methane, ethane, propane,etc.) can be pyrolized or cracked to synthesize hydrogen and to producehigher-order carbon substances (e.g., graphene and fullerenes). However,some of the processes used to produce these higher-order carbonsubstances require the use of catalysts, such as metal catalysts.Additionally, some processes result in the presence of impurities withinthe higher-order carbon substances. Furthermore, some processes requirethe formation of a “seed” or “core” around which the higher-order carbonsubstances are formed.

Different allotropes of carbon can be generated by cracking hydrocarbonsutilizing thermal processes. One example of a process for generatinglower-order carbon substances (e.g., carbon black) is the solarthermolysis of methane (both with and without a catalyst) to producehydrogen and carbon black. An example of a process for generatinghigher-order carbon substances is the catalytic decomposition of methanein a quartz tubular reactor to produce hydrogen and highly graphiticcarbon nanotubes, microfibers, microballs, and carbon onions.

FIG. 1A shows a schematic of graphite, where carbon forms multiplelayers of a two-dimensional, atomic-scale, hexagonal lattice in whichone atom forms each vertex. Graphene is a single layer of graphite. FIG.1B shows a schematic of a carbon nanotube, where carbon atoms form ahexagonal lattice that is curved into a cylinder. Carbon nanotubes canalso be referred to as cylindrical fullerenes. FIG. 1C shows a schematicof a C60 buckminsterfullerene, where a single layer of a hexagonallattice of carbon atoms forms a sphere. Other spherical fullerenes existthat contain single layers of hexagonal lattices of carbon atoms, andcan contain 60 atoms, 70 atoms, or more than 70 atoms. FIG. 1D shows aschematic of a carbon nano-onion from U.S. Pat. No. 6,599,492, whichcontains multiple concentric layers of spherical fullerenes.

SUMMARY

In some embodiments, a carbon nanoparticle comprises at least twoconnected multi-walled spherical fullerenes, and layers of graphenecoating the connected multi-walled spherical fullerenes. In someembodiments, a Raman spectrum of the carbon nanoparticle using 532 nmincident light has a first Raman peak at approximately 1350 cm⁻¹ and asecond Raman peak at approximately 1580 cm⁻¹, and a ratio of anintensity of the first Raman peak to an intensity of the second Ramanpeak is from 0.9 to 1.1. In some embodiments, a ratio of graphene tomulti-walled spherical fullerenes is from 10% to 80%.

In some embodiments, the carbon nanoparticle described above containsmulti-walled spherical fullerenes that do not comprise a seed particleor a void at the center of the multi-walled spherical fullerenes. Insome embodiments, the carbon nanoparticle described above containsmulti-walled spherical fullerenes that have an average diameter from 50nm to 500 nm.

In some embodiments, a carbon aggregate comprises a plurality of thecarbon nanoparticles described above, wherein a diameter across thecarbon aggregate is from 10 microns to 500 microns. In some embodimentsthe carbon aggregate has a ratio of graphene to multi-walled sphericalfullerenes from 10% to 80%. In some embodiments, the carbon aggregatehas a ratio of carbon to other elements, except H, in the carbonaggregate is greater than 99.9%. In some embodiments, the carbonaggregate has a Brunauer, Emmett and Teller (BET) specific surface areaof the carbon aggregate is from 10 m²/g to 200 m²/g. In someembodiments, a plurality of the carbon aggregates are compressed into apellet, and the pellet has an electrical conductivity from 500 S/m to20000 S/m.

In some embodiments, a mixture comprises a liquid and a plurality of thecarbon nanoparticles described above. In some embodiments, a conductiveink comprises a plurality of the carbon nanoparticles described above.

In some embodiments a method comprises flowing a hydrocarbon feedstockprocess gas into a reaction zone, thermally cracking molecules of thefeedstock process gas in the reaction zone, reacting the thermallycracked molecules to form carbon aggregates, each comprising at leasttwo connected multi-walled spherical fullerenes coated in layers ofgraphene, and collecting the carbon aggregates. In some embodiments, aRaman spectrum of the carbon aggregates using 532 nm incident light hasa first Raman peak at about 1350 cm-1 and a second Raman peak at about1580 cm-1, and a ratio of an intensity of the first Raman peak to anintensity of the second Raman peak is from 0.9 to 1.1. In someembodiments, the collected carbon aggregates are size-reduced bymechanical means.

In some embodiments, the multi-walled spherical fullerenes producedusing the method described above do not comprise a seed particle or avoid at the center of the multi-walled spherical fullerenes. In someembodiments, the multi-walled spherical fullerenes produced using themethod described above have an average diameter across the carbonaggregates is from 10 microns to 500 microns. In some embodiments, themulti-walled spherical fullerenes produced using the method describedabove have an average diameter from 50 nm to 500 nm. In someembodiments, the multi-walled spherical fullerenes produced using themethod described above have a ratio of graphene to multi-walledspherical fullerenes is from 10% to 80%. In some embodiments, themulti-walled spherical fullerenes produced using the method describedabove have a ratio of carbon to other elements, except H, in the carbonaggregates is greater than 99.9%. In some embodiments, the multi-walledspherical fullerenes produced using the method described above have aBrunauer, Emmett and Teller (BET) specific surface area of the carbonaggregates is from 10 m2/g to 200 m2/g.

In some embodiments, the carbon aggregates are produced by the methoddescribed above, and then compressed into a pellet, wherein the pellethas an electrical conductivity from 500 S/m to 20000 S/m. In someembodiments, the carbon aggregates are produced by the method describedabove, using a gas resonance time of 0.1 seconds to 30 seconds. In someembodiments, the carbon aggregates are produced by the method describedabove, using a gas flow rate of 1 slm to 10 slm and a production ratefrom 10 g/hr to 200 g/hr.

In some embodiments, the carbon aggregates are produced by the methoddescribed above, and then post-processed using a method selected fromgroup consisting of chemical etching, thermal annealing, particlesintering, spark plasma sintering, steaming, filtering, lypolizing,processing using Hummers' method, doping, and adding elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are schematics of carbon allotropes from the prior art.

FIG. 2 is a schematic of idealized connected multi-walled sphericalfullerenes, in accordance with some embodiments.

FIGS. 3A-3C show TEM images and Raman spectra from as-synthesized carbonaggregates in a first example, in accordance with some embodiments.

FIGS. 4A-4C show TEM images and Raman spectra from size-reduced carbonaggregates in a first example, in accordance with some embodiments.

FIGS. 5A-5D show TEM images and Raman spectra from as-synthesized carbonaggregates in a second example, in accordance with some embodiments.

FIGS. 6A-6C show TEM images and Raman spectra from size-reduced carbonaggregates in a second example, in accordance with some embodiments.

FIG. 7 depicts a simplified schematic view of a cracking apparatus inaccordance with at least some embodiments.

FIG. 8 depicts a simplified schematic view of a cracking apparatus inaccordance with at least some embodiments.

DETAILED DESCRIPTION

The present disclosure relates to carbon nanoparticles and aggregatesthat include different allotropes of (i.e., various forms of) carbon,including graphene, various fullerenes, and combinations thereof, asdescribed below. In some embodiments, the carbon nanoparticles andaggregates are characterized by a high “uniformity” (i.e., high massfraction of desired carbon allotropes), high degree of “order” (i.e.,low concentration of defects), and/or high “purity” (i.e., lowconcentration of elemental impurities), in contrast to the loweruniformity, less ordered and lower purity particles achievable withconventional systems and methods. In some embodiments, the carbonnanoparticles and aggregates described herein are characterized by asize that is substantially larger than comparable prior art particles.In some embodiments, the carbon nanoparticles and aggregates describedherein are characterized by a well-ordered structure with high purity asillustrated by an idealized carbon nanoparticle 200 shown in FIG. 2. Thecarbon allotrope in FIG. 2 contains two connected multi-walled sphericalfullerenes (MWSFs) 201 and 202 with layers of graphene 203 coating theconnected MWSFs 201 and 202). The allotrope shown in FIG. 2 is alsocore-less (i.e., does not contain a core of a material other than carbonat the center of the spherical fullerene).

The idealized nanoparticle shown in FIG. 2 has high uniformity since theratio of MWSFs to graphene is high, is well-ordered since there are nopoint defects (e.g., missing carbon atoms) and no distorted carbonlattices, and has a high purity since there are no elements (e.g., acore of impurities) other than carbon, in contrast with low uniformitymixtures of MWSFs mixed with other carbon allotropes, poorly-orderedMWSFs with many point defects and distorted lattices, and low purityMWSFs (e.g., with seed particles at the core). In other embodiments, theconnected MWSFs do contain a core. In some embodiments, the core is avoid, a carbon-based material that is not an MWSF (e.g., amorphouscarbon), or a seed that is not carbon-based.

In some embodiments, the nanoparticles produced using the methodsdescribed herein contain MWSFs or connected MWSFs and have a highuniformity (e.g., a ratio of graphene to MWSF from 20% to 80%), a highdegree of order (e.g., a Raman signature with an ID/IG ratio from 0.95to 1.05), and a high purity (e.g., the ratio of carbon to otherelements, other than H, is greater than 99.9%). In some embodiments, thenanoparticles produced using the methods described herein contain MWSFsor connected MWSFs, and the MWSFs do not contain a core composed ofimpurity elements other than carbon. In some cases, the particlesproduced using the methods described herein are aggregates containingthe nanoparticles described above with large diameters (e.g., greaterthan 10 microns across).

Conventional methods have been used to produce particles containingmulti-walled spherical fullerenes (MWSFs) with a high degree of order,but the conventional methods lead to carbon products with a variety ofshortcomings. For example, high temperature synthesis techniques lead toparticles with a mixture of many carbon allotropes and therefore lowuniformity (e.g., less than 20% fullerenes to other carbon allotropes)and/or small particle sizes (e.g., less than 1 micron, or less than 100nm in some cases). Methods utilizing catalysts lead to productsincluding the catalyst elements and therefore have low purity (e.g.,less than 95% carbon to other elements). These undesirable propertiesalso often lead to undesirable electrical properties of the resultingcarbon particles (e.g., electrical conductivity less than 1000 S/m).

In some embodiments, the carbon nanoparticles and aggregates describedherein are characterized by Raman spectroscopy that is indicative of thehigh degree of order, and the uniformity of the structure. In someembodiments, the uniform, ordered and/or pure carbon nanoparticles andaggregates described herein are produced using relatively high speed,low cost improved thermal reactors and methods, as described below.Additional advantages and/or improvements will also become apparent fromthe following disclosure.

In the present disclosure, the term “graphene” refers to an allotrope ofcarbon in the form of a two-dimensional, atomic-scale, hexagonal latticein which one atom forms each vertex. The carbon atoms in graphene aresp2-bonded. Additionally, graphene has a Raman spectrum with two mainpeaks: a G-mode at approximately 1580 cm⁻¹ and a D-mode at approximately1350 cm⁻¹ (when using a 532 nm excitation laser). In the presentdisclosure, the term “fullerene” refers to a molecule of carbon in theform of a hollow sphere, ellipsoid, tube, or other shapes. Sphericalfullerenes can also be referred to as Buckminsterfullerenes, or buckyballs. Cylindrical fullerenes can also be referred to as carbonnanotubes. Fullerenes are similar in structure to graphite, which iscomposed of stacked graphene sheets of linked hexagonal rings.

Fullerenes may also contain pentagonal (or sometimes heptagonal) rings.

In the present disclosure, the term “multi-walled fullerene” refers tofullerenes with multiple concentric layers. For example, multi-wallednanotubes (MWNTs) contain multiple rolled layers (concentric tubes) ofgraphene. Multi-walled spherical fullerenes (MWSFs) contain multipleconcentric spheres of fullerenes.

In the present disclosure, the term “nanoparticle” refers to a particlethat has a size from 1 nm to 900 nm. The nanoparticle can include one ormore type of structure (e.g., crystal structure, defect concentration,etc.), and one or more type of atom. The nanoparticle can be any shape,including but not limited to spherical shapes, spheroidal shapes,dumbbell shapes, cylindrical shapes, elongated cylindrical type shapes,rectangular prism shapes, disk shapes, wire shapes, irregular shapes,dense shapes (i.e., with few voids), porous shapes (i.e., with manyvoids), etc.

In the present disclosure, the term “aggregate” refers to a plurality ofnanoparticles that are connected together by Van der Waals forces, bycovalent bonds, by ionic bonds, by metallic bonds, or by other physicalor chemical interactions. Aggregates can vary in size considerably, butin general are larger than about 500 nm.

In some embodiments, a carbon nanoparticle, as described herein,includes two or more connected multi-walled spherical fullerenes (MWSFs)and layers of graphene coating the connected MWSFs. In some embodiments,a carbon nanoparticle, as described herein, includes two or moreconnected multi-walled spherical fullerenes (MWSFs) and layers ofgraphene coating the connected MWSFs, and the MWSFs do not contain acore composed of impurity elements other than carbon. In someembodiments, a carbon nanoparticle, as described herein, includes two ormore connected multi-walled spherical fullerenes (MWSFs) and layers ofgraphene coating the connected MWSFs, and the MWSFs do not contain avoid (i.e., a space with no carbon atoms greater than approximately 0.5nm, or 1 nm) at the center. In some embodiments, the connected MWSFs areformed of concentric, well-ordered spheres of sp2-hybridized carbonatoms, as contrasted with spheres of poorly-ordered, non-uniform,amorphous carbon particles.

In some embodiments, the nanoparticles containing the connected MWSFshave an average diameter in a range from 5 to 500 nm, or from 5 to 250nm, or from 5 to 100 nm, or from 5 to 50 nm, or from 10 to 500 nm, orfrom 10 to 250 nm, or from 10 to 100 nm, or from 10 to 50 nm, or from 40to 500 nm, or from 40 to 250 nm, or from 40 to 100 nm, or from 50 to 500nm, or from 50 to 250 nm, or from 50 to 100 nm.

In some embodiments, the carbon nanoparticles described herein formaggregates, wherein many nanoparticles aggregate together to form alarger unit. In some embodiments, a carbon aggregate includes aplurality of carbon nanoparticles. A diameter across the carbonaggregate is in a range from 10 to 500 microns, or from 50 to 500microns, or from 100 to 500 microns, or from 250 to 500 microns, or from10 to 250 microns, or from 10 to 100 microns, or from 10 to 50 microns.In some embodiments, the aggregate is formed from a plurality of carbonnanoparticles, as defined above. In some embodiments, aggregates containconnected MWSFs. In some embodiments, the aggregates contain connectedMWSFs with high uniformity (e.g., a ratio of graphene to MWSF from 20%to 80%), a high degree of order (e.g., a Raman signature with an ID/IGratio from 0.95 to 1.05), and a high purity (e.g., greater than 99.9%carbon).

One benefit of producing aggregates of carbon nanoparticles,particularly with diameters in the ranges described above, is thataggregates of particles greater than 10 microns are easier to collectthan particles or aggregates of particles that are smaller than 500 nm.The ease of collection reduces the cost of manufacturing equipment usedin the production of the carbon nanoparticles and increases the yield ofthe carbon nanoparticles. Additionally, particles greater than 10microns in size pose fewer safety concerns compared to the risks ofhandling smaller nanoparticles, e.g., potential health and safety risksdue to inhalation of the smaller nanoparticles. The lower health andsafety risks, thus, further reduce the manufacturing cost.

In some embodiments, a carbon nanoparticle has a ratio of graphene toMWSFs from 10% to 90%, or from 10% to 80% or from 10% to 60%, or from10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%,or from 40% to 90%, or from 60% to 90%, or from 80% to 90%. In someembodiments, a carbon aggregate has a ratio of graphene to MWSFs is from10% to 90%, or from 10% to 80% or from 10% to 60%, or from 10% to 40%,or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40%to 90%, or from 60% to 90%, or from 80% to 90%. In some embodiments, acarbon nanoparticle has a ratio of graphene to connected MWSFs from 10%to 90%, or from 10% to 80% or from 10% to 60%, or from 10% to 40%, orfrom 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to90%, or from 60% to 90%, or from 80% to 90%. In some embodiments, acarbon aggregate has a ratio of graphene to connected MWSFs is from 10%to 90%, or from 10% to 80% or from 10% to 60%, or from 10% to 40%, orfrom 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to90%, or from 60% to 90%, or from 80% to 90%.

In some embodiments, Raman spectroscopy is used to characterize carbonallotropes to distinguish their molecular structures. For example,graphene can be characterized using Raman spectroscopy to determineinformation such as order/disorder, edge and grain boundaries,thickness, number of layers, doping, strain, and thermal conductivity.MWSFs have also been characterized using Raman spectroscopy to determinethe degree of order of the MWSFs.

In some embodiments, Raman spectroscopy is used to characterize thestructure of MWSFs or connected MWSFs. The main peaks in the Ramanspectra are the G-mode and the D-mode. The G-mode is attributed to thevibration of carbon atoms in sp2-hybridized carbon networks, and theD-mode is related to the breathing of hexagonal carbon rings withdefects. When using 532 nm incident light, the Raman G-mode is typicallyat 1582 cm⁻¹ for planar graphite, but can be downshifted for MWSFs orconnected MWSFs (e.g., to 1565-1580 cm⁻¹). The D-mode is observed atapproximately 1350 cm⁻¹ in the Raman spectra of MWSFs or connectedMWSFs. The ratio of the intensities of the D-mode peak to G-mode peak(i.e., the ID/IG) is related to the degree of order of the MWSFs, wherea lower ID/IG indicates higher degree of order. An ID/IG near or below 1indicates a relatively high degree of order, and a ID/IG greater than1.1 indicates lower degree of order.

In some embodiments, a carbon nanoparticle or a carbon aggregatecontaining MWSFs or connected MWSFs, as described herein, has a Ramanspectrum with a first Raman peak at about 1350 cm⁻¹ and a second Ramanpeak at about 1580 cm⁻¹, when using 532 nm incident light. In someembodiments, the ratio of an intensity of the first Raman peak to anintensity of the second Raman peak (i.e., the ID/IG) for thenanoparticles or the aggregates described herein is in a range from 0.95to 1.05, or from 0.9 to 1.1, or from 0.8 to 1.2, or from 0.9 to 1.2, orfrom 0.8 to 1.1, or from 0.5 to 1.5, or less than 1.5, or less than 1.2,or less than 1.1, or less than 1, or less than 0.95, or less than 0.9,or less than 0.8.

In some embodiments, a carbon aggregate containing MWSFs or connectedMWSFs, as defined above, has high purity. In some embodiments, thecarbon aggregate containing MWSFs or connected MWSFs has a ratio ofcarbon to metals of greater than 99.99%, or greater than 99.95%, orgreater than 99.9%, or greater than 99.8%, or greater than 99.5%, orgreater than 99%. In some embodiments, the carbon aggregate has a ratioof carbon to other elements of greater than 99.99%, or greater than99.95%, or greater than 99.9%, or greater than 99.5%, or greater than99%, or greater than 90%, or greater than 80%, or greater than 70%, orgreater than 60%. In some embodiments, the carbon aggregate has a ratioof carbon to other elements, except H, of greater than 99.99%, orgreater than 99.95%, or greater than 99.9%, or greater than 99.8%, orgreater than 99.5%, or greater than 99%, or greater than 90%, or greaterthan 80%, or greater than 70%, or greater than 60%.

In some embodiments, a carbon aggregate containing MWSFs or connectedMWSFs, as defined above, has high specific surface area. In someembodiments, the carbon aggregate has a Brunauer, Emmett and Teller(BET) specific surface area from 10 to 200 m²/g, or from 10 to 100 m²/g,or from 10 to 50 m²/g, or from 50 to 200 m²/g, or from 50 to 100 m²/g,or from 10 to 1000 m²/g.

In some embodiments, a carbon aggregate containing MWSFs or connectedMWSFs, as defined above, has high electrical conductivity. In someembodiments, a carbon aggregate containing MWSFs or connected MWSFs, asdefined above, is compressed into a pellet and the pellet has electricalconductivity greater than 500 S/m, or greater than 1000 S/m, or greaterthan 2000 S/m, or greater than 3000 S/m, or greater than 4000 S/m, orgreater than 5000 S/m, or greater than 10000 S/m, or greater than 20000S/m, or greater than 30000 S/m, or greater than 40000 S/m, or greaterthan 50000 S/m, or greater than 60000 S/m, or greater than 70000 S/m, orfrom 500 S/m to 100000 S/m, or from 500 S/m to 1000 S/m, or from 500 S/mto 10000 S/m, or from 500 S/m to 20000 S/m, or from 500 S/m to 100000S/m, or from 1000 S/m to 10000 S/m, or from 1000 S/m to 20000 S/m, orfrom 10000 to 100000 S/m, or from 10000 S/m to 80000 S/m, or from 500S/m to 10000 S/m. In some cases, the density of the pellet isapproximately 1 g/cm³, or approximately 1.2 g/cm³, or approximately 1.5g/cm³, or approximately 2 g/cm³, or approximately 2.2 g/cm³, orapproximately 2.5 g/cm³, or approximately 3 g/cm³. Additionally, testshave been performed in which compressed pellets of the carbon aggregatematerials have been formed with compressions of 2000 psi and 12000 psiand with annealing temperatures of 800 C and 1000 C. The highercompression and/or the higher annealing temperatures generally resultedin pellets with higher electrical conductivity, including in a range of12410.0 S/m to 13173.3 S/m.

High Purity Carbon Allotropes Produced Using Thermal Processing Systems

In some embodiments, the carbon nanoparticles and aggregates describedherein are produced using thermal reactors and methods, such as anyappropriate thermal reactor and/or method described in theaforementioned U.S. patent application Ser. No. 15/470,450, which isassigned to the same assignee as the present application, and which isincorporated herein by reference as if fully set forth herein for allpurposes. Additionally, precursors (e.g., including methane, ethane,propane, butane, and natural gas) can be used with the thermal reactorsto produce the carbon nanoparticles and the carbon aggregates describedherein.

In some embodiments, the carbon nanoparticles and aggregates describedherein are produced using the thermal reactors with gas flow rates from1 slm (standard liter per minute) to 10 slm, or from 0.1 slm to 20 slm,or from 1 slm to 5 slm, or from 5 slm to 10 slm, or greater than 1 slm,or greater than 5 slm. In some embodiments, the carbon nanoparticles andaggregates described herein are produced using the thermal reactors withgas resonance times from 0.1 seconds to 30 seconds, or from 0.1 secondsto 10 seconds, or from 1 seconds to 10 seconds, or from 1 seconds to 5seconds, from 5 seconds to 10 seconds, or greater than 0.1 seconds, orgreater than 1 seconds, or greater than 5 seconds, or less than 30seconds.

In some embodiments, the carbon nanoparticles and aggregates describedherein are produced using the thermal reactors with production ratesfrom 10 g/hr to 200 g/hr, or from 30 g/hr to 200 g/hr, or from 30 g/hrto 100 g/hr, or from 30 g/hr to 60 g/hr, or from 10 g/hr to 100 g/hr, orgreater than 10 g/hr, or greater than 30 g/hr, or greater than 100 g/hr.

In some embodiments, thermal reactors (or cracking apparatuses) andmethods can be used for refining, pyrolizing, dissociating or crackingfeedstock process gases into constituent components to produce thecarbon nanoparticles and the carbon aggregates described herein, as wellas other solid and/or gaseous products (e.g., hydrogen gas and/or lowerorder hydrocarbon gases). The feedstock process gases generally include,for example, hydrogen gas (H2), carbon dioxide (CO2), C1-10hydrocarbons, aromatic hydrocarbons, other hydrocarbon gases, naturalgas, methane, ethane, propane, butane, isobutane, saturated/unsaturatedhydrocarbon gases, ethene, propene, etc. and mixtures thereof. Thecarbon nanoparticles and the carbon aggregates can include, for example,multi-walled spherical fullerenes (MWSFs), connected MWSFs, carbonnanospheres, graphene, graphite, highly ordered pyrolytic graphite,single walled nanotubes, multi-walled nanotubes, other solid carbonproducts, and/or the carbon nanoparticles and the carbon aggregatesdescribed herein.

Some embodiments for producing the carbon nanoparticles and the carbonaggregates described herein include thermal cracking methods that use,for example, an elongated longitudinal heating element optionallyenclosed within an elongated casing, housing or body of a thermalcracking apparatus. The body generally includes, for example, one ormore tubes or other appropriate enclosures made of stainless steel,titanium, graphite, quartz, or the like. In some embodiments, the bodyof the thermal cracking apparatus is generally cylindrical in shape witha central elongate longitudinal axis arranged vertically and a feedstockprocess gas inlet at or near a top of the body. The feedstock processgas flows longitudinally down through the body or a portion thereof. Inthe vertical configuration, both gas flow and gravity assist in theremoval of the solid products from the body of the thermal crackingapparatus.

The heating element generally includes, for example, a heating lamp, oneor more resistive wires or filaments (or twisted wires), metalfilaments, metallic strips or rods, and/or other appropriate thermalradical generators or elements that can be heated to a specifiedtemperature (i.e., a molecular cracking temperature) sufficient tothermally crack molecules of the feedstock process gas. The heatingelement is generally disposed, located or arranged to extend centrallywithin the body of the thermal cracking apparatus along the centrallongitudinal axis thereof. For example, if there is only one heatingelement, then it is placed at or concentric with the centrallongitudinal axis, and if there is a plurality of the heating elements,then they are spaced or offset generally symmetrically or concentricallyat locations near and around and parallel to the central longitudinalaxis.

Thermal cracking to produce the carbon nanoparticles and aggregatesdescribed herein is generally achieved by passing the feedstock processgas over, in contact with, or within the vicinity of, the heatingelement within a longitudinal elongated reaction zone generated by heatfrom the heating element and defined by and contained inside the body toheat the feedstock process gas to or at a specified molecular crackingtemperature, e.g., 600-3000° C. or 1600-2200° C. The reaction zone isconsidered to be the region surrounding the heating element and closeenough to the heating element for the feedstock process gas to receivesufficient heat to thermally crack the molecules thereof. The reactionzone is thus generally axially aligned or concentric with the centrallongitudinal axis of the body. In some embodiments, the thermal crackingis performed under a specified pressure. In some embodiments, thefeedstock process gas is circulated around or across the outside surfaceof a container of the reaction zone or a heating chamber in order tocool the container or chamber and preheat the feedstock process gasbefore flowing the feedstock process gas into the reaction zone.

In some embodiments, the carbon nanoparticles and aggregates describedherein and/or hydrogen gas are produced without the use of catalysts. Inother words, the process is catalyst-free.

Some embodiments to produce the carbon nanoparticles and aggregatesdescribed herein using thermal cracking apparatuses and methods providea standalone system that can advantageously be rapidly scaled up orscaled down for different production levels as desired. For example,some embodiments are scalable to provide a standalone hydrogen and/orcarbon nanoparticle producing station system, a hydrocarbon source or afuel cell station. Some embodiments can be scaled up to provide highercapacity systems, e.g., for a refinery or the like.

In some embodiments, a thermal cracking apparatus for cracking afeedstock process gas to produce the carbon nanoparticles and aggregatesdescribed herein includes a body, a feedstock process gas inlet, and anelongated heating element. The body has an inner volume with alongitudinal axis. The inner volume has a reaction zone concentric withthe longitudinal axis. A feedstock process gas is flowed into the innervolume through the feedstock process gas inlet during thermal crackingoperations. The elongated heating element is disposed within the innervolume along the longitudinal axis and is surrounded by the reactionzone. During the thermal cracking operations, the elongated heatingelement is heated by electrical power to a molecular crackingtemperature to generate the reaction zone, the feedstock process gas isheated by heat from the elongated heating element, and the heatthermally cracks molecules of the feedstock process gas that are withinthe reaction zone into constituent components of the molecules.

In some embodiments, a method for cracking a feedstock process gas toproduce the carbon nanoparticles and aggregates described hereinincludes providing a thermal cracking apparatus having an inner volumethat has a longitudinal axis and an elongated heating element disposedwithin the inner volume along the longitudinal axis; heating theelongated heating element by electrical power to a molecular crackingtemperature to generate a longitudinal elongated reaction zone withinthe inner volume; flowing a feedstock process gas into the inner volumeand through the longitudinal elongated reaction zone, wherein thefeedstock process gas is heated by heat from the elongated heatingelement; thermally cracking molecules of the feedstock process gaswithin the longitudinal elongated reaction zone into constituentcomponents thereof (e.g., hydrogen gas and one or more solid products)as the feedstock process gas flows through the longitudinal elongatedreaction zone; and collecting the constituent components.

In some embodiments, the feedstock process gas to produce the carbonnanoparticles and aggregates described herein includes a hydrocarbongas, and the constituent components include hydrogen and the carbonnanoparticles and aggregates described herein. In some embodiments, thecarbon nanoparticles and aggregates include two or more MWSFs and layersof graphene coating the MWSFs, and/or connected MWSFs and layers ofgraphene coating the connected MWSFs. In some embodiments, the feedstockprocess gas is preheated (e.g., to 100-500° C.) by flowing the feedstockprocess gas through a gas preheating region between a heating chamberand a shell of the thermal cracking apparatus before flowing thefeedstock process gas into the inner volume. In some embodiments, a gashaving nanoparticles therein is flowed into the inner volume and throughthe longitudinal elongated reaction zone to mix with the feedstockprocess gas; and a coating of a solid product (e.g., layers of graphene)is formed around the nanoparticles.

Additional information and embodiments for thermal cracking systemmethods and apparatuses to produce the carbon nanoparticles andaggregates described herein are described in the aforementioned U.S.patent application Ser. No. 15/470,450.

Post-Processing High Purity Carbon Allotropes

In some embodiments, the carbon nanoparticles and aggregates containingmulti-walled spherical fullerenes (MWSFs) or connected MWSFs describedherein are produced and collected, and no post-processing is done. Inother embodiments, the carbon nanoparticles and aggregates containingmulti-walled spherical fullerenes (MWSFs) or connected MWSFs describedherein are produced and collected, and some post-processing is done.Some examples of post-processing include mechanical processing, such asball milling, grinding, attrition milling, micro-fluidizing, and othertechniques to reduce the particle size without damaging the MWSFs. Someexamples of post-processing include exfoliation processes such as sheermixing, chemical etching, oxidizing (e.g., Hummer method), thermalannealing, doping by adding elements during annealing (e.g., S, and N),steaming, filtering, and lypolizing, among others. Some examples ofpost-processing include sintering processes such as SPS (Spark PlasmaSintering, i.e., Direct Current Sintering), Microwave, and UV(Ultra-Violet), which can be conducted at high pressure and temperaturein an inert gas. In some embodiments, multiple post-processing methodscan be used together or in series. In some embodiments, thepost-processing will produce functionalized carbon nanoparticles oraggregates containing multi-walled spherical fullerenes (MWSFs) orconnected MWSFs.

In some embodiments, the materials are mixed together in differentcombinations. In some embodiments, different carbon nanoparticles andaggregates containing MWSFs or connected MWSFs described herein aremixed together before post-processing. For example, different carbonnanoparticles and aggregates containing MWSFs or connected MWSFs withdifferent properties (e.g., different sizes, different compositions,different purities, from different processing runs, etc.) can be mixedtogether. In some embodiments, the carbon nanoparticles and aggregatescontaining MWSFs or connected MWSFs described herein could be mixed withgraphene to change the ratio of the connected MWSFs to graphene in themixture. In some embodiments, different carbon nanoparticles andaggregates containing MWSFs or connected MWSFs described herein aremixed together after post-processing. For example, different carbonnanoparticles and aggregates containing MWSFs or connected MWSFs withdifferent properties and/or different post-processing methods (e.g.,different sizes, different compositions, different functionality,different surface properties, different surface areas) can be mixedtogether.

In some embodiments, the carbon nanoparticles and aggregates describedherein are produced and collected, and subsequently processed bymechanical grinding, milling, or exfoliating. In some embodiments, theprocessing (e.g., by mechanical grinding, milling, exfoliating, etc.)reduces the average size of the particles. In some embodiments, theprocessing (e.g., by mechanical grinding, milling, exfoliating, etc.)increases the average surface area of the particles. In someembodiments, the processing by mechanical grinding, milling orexfoliation shears off some fraction of the carbon layers, producingsheets of graphite mixed with the carbon nanoparticles. In someembodiments, the mechanical grinding or milling is performed using aball mill, a planetary mill, a rod mill, a shear mixer, high-sheargranulator, an autogenous mill, or other type of machine used to breaksolid materials into smaller pieces by grinding, crushing or cutting. Insome embodiments, the mechanical grinding, milling or exfoliating isperformed wet or dry. In some embodiments, the mechanical grinding isperformed by grinding for some period of time, then idling for someperiod of time, and repeating the grinding and idling for a number ofcycles. In some embodiments, the grinding period is from 1 minute to 20minutes, or from 1 minute to 10 minutes, or from 3 minutes to 8 minutes,or approximately 3 minutes, or approximately 8 minutes. In someembodiments, the idling period is from 1 minute to 10 minutes, orapproximately 5 minutes, or approximately 6 minutes. In someembodiments, the number of grinding and idling cycles is from 1 to 100,or from 5 to 100, or from 10 to 100, or from 5 to 10, or from 5 to 20.In some embodiments, the total amount of time grinding and idling isfrom 10 minutes to 1200 minutes, or from 10 minutes to 600 minutes, orfrom 10 minutes to 240 minutes, or from 10 minutes to 120 minutes, orfrom 100 minutes to 90 minutes, or from 10 minutes to 60 minutes, orapproximately 90 minutes, or approximately 120 minutes.

In some embodiments, the grinding steps in the cycle are performed byrotating a mill in one direction for a first cycle (e.g., clockwise),and then rotating a mill in the opposite direction (e.g.,counter-clockwise) for the next cycle. In some embodiments, themechanical grinding or milling is performed using a ball mill, and thegrinding steps are performed using a rotation speed from 100 to 1000rpm, or from 100 to 500 rpm, or approximately 400 rpm. In someembodiments, the mechanical grinding or milling is performed using aball mill using a milling media with a diameter from 0.1 mm to 20 mm, orfrom 0.1 mm to 10 mm, or from 1 mm to 10 mm, or approximately 0.1 mm, orapproximately 1 mm, or approximately 10 mm. In some embodiments, themechanical grinding or milling is performed using a ball mill using amilling media composed of metal such as steel, an oxide such aszirconium oxide (zirconia), yttria stabilized zirconium oxide, silica,alumina, magnesium oxide, or other hard materials such as siliconcarbide or tungsten carbide.

In some embodiments, the carbon nanoparticles and aggregates describedherein are produced and collected, and subsequently processed usingelevated temperatures, such as thermal annealing, or sintering. In someembodiments, the processing using elevated temperatures is done in aninert environment such as nitrogen or argon. In some embodiments, theprocessing using elevated temperatures is done at atmospheric pressure,or under vacuum, or at low pressure. In some embodiments, the processingusing elevated temperatures is done at a temperature from 500° C. to2500° C., or from 500° C. to 1500° C., or from 800° C. to 1500° C., orfrom 800° C. to 1200° C., or from 800° C. to 1000° C., or from 2000 to2400° C., or approximately 800° C., or approximately 1000° C., orapproximately 1500° C., or approximately 2000° C., or approximately2400° C.

In some embodiments, the carbon nanoparticles and aggregates describedherein are produced and collected, and subsequently additional elementsor compounds are added, thereby incorporating the unique properties ofthe carbon nanoparticles and aggregates into other mixtures ofmaterials. For example, nickel can be added to increase the magneticpermeability of the carbon nanoparticles and aggregates, or the degreeof magnetization that the carbon nanoparticles and aggregates obtain inresponse to an applied magnetic field. Another example is the additionof sulfur to increase the surface area of the carbon nanoparticles andaggregates by forcing the carbon layers to separate. For example, addingsulfur can increase the surface area by 2 or 3 times compared with thematerial without sulfur. Another method to increase the surface area isthrough oxidation, however, the resulting compounds (e.g., grapheneoxide) are insulators. The methods described herein, e.g., using sulfur,can produce particles with high surface areas that are conductive.

In some embodiments, either before or after post-processing, the carbonnanoparticles and aggregates described herein are added to solids,liquids or slurries of other elements or compounds to form additionalmixtures of materials incorporating the unique properties of the carbonnanoparticles and aggregates. In some embodiments, the carbonnanoparticles and aggregates described herein are mixed with other solidparticles, polymers or other materials. The resulting powders orcomposites of the particles in a solid matrix of a different material,can be used in different applications, such as in lubricants orstructural composite materials. In some embodiments, the carbonnanoparticles and aggregates described herein are mixed with liquids toproduce inks for different applications, such as conductive inks. Theresulting inks can also be coated on a substrate or infused in anothermaterial for various applications such as capacitor or batteryelectrodes. In some embodiments, the carbon nanoparticles and aggregatesdescribed herein are mixed with solvents and optionally other particlesto create slurries, which can then be coated or printed onto othersurfaces in various applications, such as printed conductor antennas.

In some embodiments, either before or after post-processing, the carbonnanoparticles and aggregates described herein are used in variousapplications, including but not limited to lubricant formulations (e.g.,lubricants for high-speed or high-stress applications, lubricants forhigh-temperature environments, lubricants for high-thermal conductivityapplications, and anti-stiction lubricants, among others), filtrationand separation applications (e.g., chemical filters, water filtration,desalinization, gas separation, oxidation barrier, impermeablemembranes, non-reactive filters, and carbon sequestration material,among others), transportation and industrial applications (e.g., rubberadditives, tire additives, automobile tire additives, major componentsin tires, functionalized additives for tires, couplings, mounts,elastomeric o-rings, hoses, sealants, and epoxies, among others),metamaterials formulations (e.g., the particles or aggregates decoratedwith Ni, Co or Fe nanowires, carbon dielectric layered materials, andinterface materials with functionalized surfaces, among othercombinations with other materials that result in unexpected properties),electronics ink formulations (e.g., conductive inks, transparentconductive inks, 3D printed circuits and PCBs, resistivity inks,dielectric inks, flexible electronics, piezoelectrics, antennas,rectennas, smart rectennas, electrochromic devices, triboelectricdevices, microwave equipment, system inks, and identification systems,among others), other inks (e.g., cosmetics, and 3D printed structuralinks, among others), coatings (e.g., anti-corrosion, super hydrophobic,room heating, de-icing, cooling, electro-static discharge (ESD),radiofrequency shielding (EMF shielding) radiofrequency absorbing (EMFabsorbing), and fabric and textile coatings, among others), capacitormaterial formulations (e.g., super capacitor additives, high surfacearea carbon, high purity carbon, high surface area high purity carbon,and separators, among others), sensors and solid state electronicsapplications (e.g., chemical, humidity, touch, light, transistors,diodes, and integrated devices, among others), composite materialsformulations (e.g., as additives for cement, steel, aluminum, plastics,and carbon fiber, among others), energy applications (e.g., hydrogenstorage, anode composites, cathode composites, batteries, fuel cellelectrodes, capacitors, and capacitor/battery hybrids, among others),in-vivo bio-medical applications (e.g., tissue engineering, drugdelivery, metal delivery, bio-degradable nanowire for neuroregeneration, and better health, among others), and ex-vivo bio-medicalapplications (e.g., filtration, skin electrodes, and other medicaldevices).

EXAMPLES Example 1: Experimental Data from Thermal Hot-Wire ProcessingSystem

For this example, the carbon nanoparticles were generated using athermal cracking apparatus, described in embodiments above. The thermalcracking apparatus had a main body made from stainless steel with aquartz inner wall material, and a heating element that includes atantalum/tungsten resistive wire. The reaction zone volume wasapproximately 2000 cm³. The precursor material was methane, and wasflowed from 5 to 10 slm. With those flow rates and the tool geometry,the resonance time of the gas in the reaction chamber was fromapproximately 0.1 second to 10 seconds, and the carbon particleproduction rate was from approximately 140 g/hr.

FIGS. 3A and 3B show TEM images of as-synthesized carbon nanoparticlesof this example. The carbon nanoparticles contain connected multi-walledspherical fullerenes (MWSFs) with layers of graphene coating theconnected MWSFs.

The ratio of MWSF to graphene allotropes in this example isapproximately 80%, due to the relatively short resonance times. TheMWSFs in FIG. 3A are approximately 5-10 nm in diameter, and the diametercan be from 5 to 500 nm using the conditions described above. In someembodiments, the average diameter across the MWSFs is in a range from 5to 500 nm, or from 5 to 250 nm, or from 5 to 100 nm, or from 5 to 50 nm,or from 10 to 500 nm, or from 10 to 250 nm, or from 10 to 100 nm, orfrom 10 to 50 nm, or from 40 to 500 nm, or from 40 to 250 nm, or from 40to 100 nm, or from 50 to 500 nm, or from 50 to 250 nm, or from 50 to 100nm. No catalyst was used in this process, and therefore, there is nocentral seed containing contaminants. The aggregate particles producedin this example had particle size of approximately 10 to 100 microns, orapproximately 10 to 500 microns. FIG. 3C shows the Raman spectrum of theas-synthesized aggregates in this example taken with 532 nm incidentlight. The ID/IG for the aggregates produced in this example is fromapproximately 0.99 to 1.03, indicating that the aggregates were composedof carbon allotropes with a high degree of order.

FIGS. 4A and 4B show TEM images of the carbon nanoparticles of thisexample after size-reduction by grinding in a ball mill. The ballmilling was performed in cycles with a 3 minute counter-clockwisegrinding step, followed by a 6 minute idle step, followed by a 3 minuteclockwise grinding step, followed by a 6 minute idle step. The grindingsteps were performed using a rotation speed of 400 rpm. The millingmedia was zirconia, and ranged in size from 0.1 mm to 10 mm. The totalsize reduction processing time was from 60 to 120 minutes. Aftersize-reduction, the aggregate particles produced in this example hadparticle size of approximately 1 to 5 microns. The carbon nanoparticlesafter size-reduction are connected MWSFs with layers of graphene coatingthe connected MWSFs. FIG. 4C shows a Raman spectrum from the aggregatesof this example after size-reduction taken with a 532 nm incident light.The ID/IG for the aggregate particles in this example aftersize-reduction is approximately 1.04. Additionally, the particles aftersize-reduction had a Brunauer, Emmett and Teller (BET) specific surfacearea of approximately 40 to 50 m²/g.

The purity of the aggregates produced in this sample were measured usingmass spectrometry and x-ray fluorescence spectroscopy (XRF). The ratioof carbon to other elements, except for H, measured in 16 differentbatches was from 99.86% to 99.98%, with an average of 99.94%.

Example 2: Experimental Data from Thermal Hot-Wire Processing System

In this example, carbon nanoparticles were generated using a thermalhot-wire processing system described in Example 1. The precursormaterial was methane, and was flowed from 1 to 5 slm. With those flowrates and the tool geometry, the resonance time of the gas in thereaction chamber was from approximately 20 second to 30 seconds, and thecarbon particle production rate was from approximately 20 g/hr.

FIGS. 5A, 5B and 5C show TEM images of as-synthesized carbonnanoparticles of this example. The carbon nanoparticles containconnected multi-walled spherical fullerenes (MWSFs) with layers ofgraphene coating the connected MWSFs. The ratio of multi-walledfullerene to graphene allotropes in this example is approximately 30%,due to the relatively long resonance times allowing thicker, or more,layers of graphene to coat the MWSFs. No catalyst was used in thisprocess, and therefore, there is no central seed containingcontaminants. The as-synthesized aggregate particles produced in thisexample had particle size of approximately 10 to 500 microns. FIG. 5Dshows a Raman spectrum from the aggregates of this example. The Ramansignature of the as-synthesized particles in this example is indicativeof the thicker graphene layers which coat the MWSFs in theas-synthesized material. Additionally, the as-synthesized particles hada Brunauer, Emmett and Teller (BET) specific surface area ofapproximately 90 to 100 m²/g.

FIGS. 6A and 6B show TEM images of the carbon nanoparticles of thisexample after size-reduction by grinding in a ball mill. Thesize-reduction process conditions were the same as those described inExample 1. After size-reduction, the aggregate particles produced inthis example had particle size of approximately 1 to 5 microns. The TEMimages show that the connected MWSFs that were buried in the graphenecoating can be observed after size-reduction. FIG. 6C shows a Ramanspectrum from the aggregates of this example after size-reduction takenwith 532 nm incident light. The ID/IG for the aggregate particles inthis example after size-reduction is approximately 1, indicating thatthe connected MWSFs that were buried in the graphene coatingas-synthesized had become detectable in Raman after size-reduction andwere well-ordered. The particles after size-reduction had a Brunauer,Emmett and Teller (BET) specific surface area of approximately 90 to 100m²/g.

Example Thermal Cracking Apparatuses

FIG. 7 depicts a simplified schematic view of a thermal crackingapparatus 1500, in accordance with at least some embodiments. Thethermal cracking apparatus 1500 generally includes a body 1502, a topcap assembly 1504, a bottom cap assembly 1506, a heating element 1508, afeedstock process gas preheat inlet 1512, a secondary feedstock processgas inlet 1514, one or more cooling gas inlets and outlets 1516 and1518, a cooling fluid inlet and outlet 1520 and 1522, and a productoutlet 1524, among other components shown (but not labeled) or not shownfor simplicity and ease of illustration and description.

The body 1502 generally includes an outer shell or housing 1526, asecondary shell 1528, an inner reactor tube (an insert or heatingchamber) 1530, and an outer reactor tube 1532. The body 1502 isconsidered a dual wall structure or dual tube reactor because itgenerally includes both of the reactor tubes 1530 and 1532 disposedwithin the shells 1526 and 1528. (In some embodiments, the outer reactortube 1532 is considered to be another shell surrounding the innerreactor tube 1530.) The shells 1526 and 1528 and the reactor tubes 1530and 1532 are generally cylindrical in shape with a central longitudinalaxis arranged vertically. The inner reactor tube 1530 is generally madeof quartz, alumina, or other appropriate material for withstanding theoperational temperatures of the reaction zone. The shells 1526 and 1528and the outer reactor tube 1532 are generally made of steel, titanium,or other appropriate materials.

The top cap assembly 1504 and the bottom cap assembly 1506 are generallymade of steel or other appropriate materials. The top cap assembly 1504and the bottom cap assembly 1506 are mounted or attached to the top andbottom, respectively, of the shells 1526 and 1528 to hold the shells1526 and 1528 in a generally concentric arrangement or relationship toeach other with a space 1534 there between. The space 1534 between theshells 1526 and 1528 defines a cooling fluid region.

A top and bottom plug, cap or insert 1536 and 1538 are disposed withinthe secondary shell 1528 near the top and bottom, respectively, of thebody 1502. The top and bottom plugs 1536 and 1538 are generally made ofsteel or other appropriate materials. The bottom plug 1538 is mounted orset within the secondary shell 1528 down against an inner surface orflange of the bottom cap assembly 1506 and engages bottom ends of thereactor tubes 1530 and 1532. The top plug 1536 is mounted or set withinthe secondary shell 1528 near a top end of the secondary shell 1528 andengages top ends of the reactor tubes 1530 and 1532. A compressionspring assembly 1540 engages the top plug 1536 and an inner surface orflange of the top cap assembly 1504 to press the top plug 1536 to thereactor tubes 1530 and 1532, the reactor tubes 1530 and 1532 to thebottom plug 1538, and the bottom plug 1538 to the inner surface orflange of the bottom cap assembly 1506, thereby holding the reactortubes 1530 and 1532 in place. The top and bottom plugs 1536 and 1538generally hold the reactor tubes 1530 and 1532 in a generally concentricarrangement or relationship to each other and to the secondary shell1528, with a space 1542 between the outer reactor tube 1532 and thesecondary shell 1528, and a space 1544 between the inner reactor tube1530 and the outer reactor tube 1532. The space 1542 between the outerreactor tube 1532 and the secondary shell 1528 defines a gas coolantregion. The space 1544 between the inner reactor tube 1530 and the outerreactor tube 1532 defines a feedstock gas preheating region.

The heating element 1508 is any appropriate type described above andextends along, generally concentrically with, and parallel to, thecentral longitudinal axis of the body 1502 or the inner reactor tube1530. The heating element 1508 is mounted or attached at a top end to atop electrode assembly 1546 that is mounted or attached to the body 1502and extends through the shells 1526 and 1528 above the top plug 1536. Inthe illustrated embodiment, the heating element 1508 is mounted orattached at a bottom end to a bottom electrode assembly 1548 and aspring bias assembly 1550. The bottom electrode assembly 1548 is mountedor attached to a lower portion 1552 of the bottom cap assembly 1506 andextends through the lower portion 1552 to contact the heating element1508 through a hole in the bottom electrode assembly 1548. The springbias assembly 1550 includes a spring 1554 within a cylindrical housing1556 that is attached or mounted to the underside of the lower portion1552 of the bottom cap assembly 1506. The heating element 1508 extendsthrough a hole in the bottom cap assembly 1506 and the hole in thebottom electrode assembly 1548 down to the bottom of the spring 1554.The heating element 1508 is attached to the bottom of the spring 1554and is held in tension by the spring 1554 acting against the undersideof the bottom electrode assembly 1548. Thus, when the heating element1508 heats up during gas processing or thermal cracking operations andcools down afterwards, any thermal expansion or contraction of theheating element 1508 is compensated for by the spring bias assembly1550, which maintains the heating element 1508 in tension, so that theheating element 1508 remains generally concentric and parallel to thecentral longitudinal axis of the body 1502 or the inner reactor tube1530.

An interior surface of a wall of the inner reactor tube 1530 defines aninner volume, all or part of which includes a longitudinal elongatedreaction zone generated in the vicinity of the heating element 1508during gas processing or thermal cracking operations. The inner reactortube 1530 is thus the heating or reaction chamber of the thermalcracking apparatus 1500, and the central longitudinal axis of the body1502 or the inner reactor tube 1530 is also considered to be a centrallongitudinal axis of the longitudinal elongated reaction zone.

Electrical power is provided to the heating element 1508 through the topelectrode assembly 1546 and the bottom electrode assembly 1548 duringgas processing operations. The top electrode assembly 1546 electricallyconnects to, or near, the top of the heating element 1508. The bottomelectrode assembly 1548 electrically connects to, or near, the bottom ofthe heating element 1508, either directly to the heating element 1508(within the hole therein) or through an electrical connection to thespring 1554.

The feedstock process gas preheat inlet 1512 is fluidly connected to afeedstock process gas source (not shown). The feedstock process gaspreheat inlet 1512 is also attached or mounted to the shells 1526 and1528 to be in fluid communication with the feedstock gas preheatingregion (space 1544) via apertures or holes through the shells 1526 and1528, the bottom plug 1538, and the outer reactor tube 1532. During gasprocessing operations, the feedstock process gas is flowed from thesource through the feedstock process gas preheat inlet 1512 and into thefeedstock process gas preheating region (space 1544). The feedstockprocess gas then circulates across the outer surface of the innerreactor tube 1530. The inner reactor tube 1530 is typically very hot dueto the thermal gas processing occurring therein. The circulation of thefeedstock process gas around the inner reactor tube 1530, thus, servesthe dual purpose of cooling the inner reactor tube 1530 and preheatingthe feedstock process gas with residual heat transferred through thewall of the inner reactor tube 1530 from the reaction zone. Forembodiments in which the gas flow direction is downward, a series ofholes or apertures 1558 in the wall of the inner reactor tube 1530 nearthe top of the feedstock gas preheating region (space 1544) allow thepreheated feedstock process gas to flow into the inner volume of theinner reactor tube 1530, i.e., the reaction zone. Within the innervolume or the reaction zone, the preheated feedstock process gascirculates around the heating element 1508, which further heats thefeedstock process gas in the vicinity thereof to thermally crack thefeedstock process gas into constituent elements and/or lower ordermolecules, i.e., the gaseous and solid products. For embodiments inwhich the gas flow direction is upward, on the other hand, the series ofholes or apertures 1558 in the wall of the inner reactor tube 1530 areplaced near the bottom of the feedstock gas preheating region (space1544) and the feedstock process gas preheat inlet 1512 is placed nearthe top of the feedstock gas preheating region.

In some embodiments, the secondary feedstock process gas inlet 1514 isfluidly connected to a source (not shown) of a gas (e.g., a secondfeedstock process gas) having additional particles (e.g., nano-particlesof Silicon (Si), Silicon Carbide (SiC), or other appropriate materialsable to withstand the high temperatures of the process without melting)floating or suspended therein. The secondary feedstock process gas inlet1514 is attached or mounted to the shells 1526 and 1528 to be in fluidcommunication with the inner volume of the inner reactor tube 1530 viaapertures through the shells 1526 and 1528, the top plug 1536, and theinner reactor tube 1530. During gas processing operations, the feedstockprocess gas with additional particles is flowed from the source throughthe secondary feedstock process gas inlet 1514, through a series ofholes or apertures 1560 (in the wall of the inner reactor tube 1530 nearthe top thereof), and into the inner volume of the inner reactor tube1530, i.e., the reaction zone. Within the inner volume or the reactionzone, the feedstock process gas with additional particles mixes with thepreheated feedstock process gas. In some embodiments, the additionalparticles have a melting point at or above about 500-1000° C. Thetemperature to which the additional particles are heated generallydepends on various process parameters, such as the temperature of theheating element 1508, the flow rate of the feedstock process gas, thelongitudinal length of the reaction zone, and the time that theadditional particles spend within the reaction zone. Therefore, sincethe process parameters are set so that the additional particles areheated to a temperature lower than their melting point when they passthrough the reaction zone, the solid carbon product (e.g., the graphene)produced from the feedstock process gas (e.g., the methane, natural gas,or other hydrocarbons) generally forms a coating around the additionalparticles. The coating generally includes one or more layers of thesolid carbon product, such as one or more concentric layers of graphene,surrounding each additional particle. In this manner, carbon-coatednano-particles are formed within the reaction zone. Additionally, insome embodiments, the additional particles act as a catalyst in thethermal cracking of the feedstock process gas in the reaction zone.

In some embodiments, the feedstock process gas having additionalparticles, the secondary feedstock process gas inlet 1514, and theseries of holes or apertures 1560 are considered optional or are notincluded in the thermal cracking apparatus 1500.

In some embodiments, the cooling gas inlet and outlet 1516 and 1518 areattached or mounted to the shells 1526 and 1528 to be in fluidcommunication with the gas coolant region, i.e., the space 1542 betweenthe outer reactor tube 1532 and the secondary shell 1528, via aperturesor holes through the shells 1526 and 1528. During gas processingoperations, a coolant gas (e.g., air, nitrogen, a noble gas, etc.) isflowed from a source thereof, through the cooling gas inlet 1516, andinto the gas coolant region (space 1542). The coolant gas thuscirculates within the gas coolant region, absorbs some of the heat fromthe outer reactor tube 1532 (thereby serving to cool the outer reactortube 1532), and exits through the outlet 1518 to be cooled, recycled,discarded or stored.

In some other embodiments, the space 1542 between the outer reactor tube1532 and the secondary shell 1528 is filled with a thermally insulatingor conducting material, rather than having a coolant gas flow therein.In various embodiments, the use or selection of the coolant gas or thethermally insulating or conducting material for the space 1542 generallydepends on the thermal requirements for the overall configuration of thethermal cracking apparatus 1500, the type of the feedstock process gas,the type or characteristics of the desired solid and/or gaseousproducts, and/or the process parameters of the gas processingoperations. Different embodiments, in other words, generally havedifferent thermal requirements.

In some embodiments, the cooling fluid inlet and outlet 1520 and 1522are attached or mounted to the outer shell 1526 to be in fluidcommunication with the cooling fluid region, i.e., the space 1534between the shells 1526 and 1528, via apertures or holes through theouter shell 1526. During gas processing operations, a coolant fluid(e.g., water, etc.) is flowed from a source thereof, through the coolingfluid inlet 1520, and into the cooling fluid region (space 1534). Thecoolant fluid thus circulates within the cooling fluid region, absorbssome of the heat from the secondary shell 1528 (thereby cooling thesecondary shell 1528), and exits through the outlet 1522 to be cooled,recycled, discarded or stored. In this manner, the action of the coolantfluid, or the combined action of the coolant fluid and the coolant gas,ensures that the outer surface of the thermal cracking apparatus 1500(i.e., of the body 1502 or the outer shell 1526) remains cool, or doesnot become too hot to pose a danger to nearby equipment or personnel.

In the illustrated embodiment, the product outlet 1524 is mounted orattached to the lower portion 1552 of the bottom cap assembly 1506 forembodiments in which the gas flow direction is downward. (Forembodiments in which the gas flow direction is upward, on the otherhand, the product outlet 1524 is mounted or attached near the top of theinner volume of the inner reactor tube 1530.) The solid and gaseousproducts generally flow out the bottom cap assembly 1506, e.g., througha series of passageways through the bottom cap assembly 1506 leading tothe product outlet 1524, and then to an appropriate storage apparatus,hopper, or other receiving mechanism 1562. In some embodiments, thegaseous and solid products enter the hopper 1562 and are exhausted witha Venturi assist and a flow of nitrogen gas. The solid products areremoved by detaching the hopper 1562 from the product outlet 1524 andpouring them out. The gaseous products are removed by flowing through agaseous product outlet 1564 from the hopper 1562. The gaseous productoutlet 1564 is mounted or attached to the hopper 1562 to provide a fluidconnection to the interior of the hopper 1562. The gaseous productoutlet 1564 is also fluidly connected to a downstream storage apparatusor further gas processing apparatus. The gaseous products are thusflowed out through the gaseous product outlet 1564 to the downstreamstorage apparatus or further gas processing apparatus. Some embodimentsincorporating an alternative exhaust system technique that may be usedwith the thermal cracking apparatus 1500, with appropriate adjustmentsor modifications thereto, are described below with respect to FIG. 8.Additionally, in some embodiments, different hoppers (e.g., having thesame or different design or configuration) are used for differentapplications. For example, one hopper is used when producing the solidcarbon products, and a different hopper is used when producing thecarbon-coated nano-particles. Thus, the bottom cap assembly 1506 and theconnection to the product outlet 1524 and/or the hopper 1562 aredesigned for removal and replacement of the hopper 1562, so that a cleanor different hopper 1562 can be attached for each application.

In some situations, some of the solid products can accumulate within theinner volume of the inner reactor tube 1530, e.g., on the interiorsurface of the wall of the inner reactor tube 1530 and/or the heatingelement 1508. Some embodiments may also use any appropriate structuresor subassemblies for forcibly removing the solid products or cleaningthe reaction zone.

FIG. 8 depicts a simplified schematic view of a thermal crackingapparatus 1600, in accordance with at least some embodiments. Some ofthe features described for the thermal cracking apparatus 1600 can beapplied to the embodiment shown for the thermal cracking apparatus 1500in FIG. 7, and some of the features described above for the thermalcracking apparatus 1500 can be applied to the embodiment for the thermalcracking apparatus 1600, as will be described below.

The thermal cracking apparatus 1600 generally includes a body 1602, atop cap assembly 1604, a bottom cap assembly 1606, a heating element1608, a feedstock process gas inlet 1612, a secondary feedstock processgas inlet 1614, one or more cooling gas inlets and outlets 1616 and1618, a cooling fluid inlet and outlet 1620 and 1622, a gaseous productoutlet 1624, and a solid product outlet 1626, among other componentsshown (but not labeled) or not shown for simplicity and ease ofillustration and description.

The body 1602 generally includes an outer shell or housing 1628, asecondary shell 1630, and a reactor tube (heating chamber) 1632. Thebody 1602 is considered a single wall structure or single tube reactorbecause it generally includes only the single reactor tube 1632 disposedwithin the shells 1628 and 1630. The single wall structure or singletube reactor embodiment of FIG. 8 is, thus, an alternative to the dualwall structure or dual tube reactor embodiment of FIG. 7. The shells1628 and 1630 and the reactor tube 1632 are generally cylindrical inshape with a central longitudinal axis arranged vertically. The reactortube 1632 is generally made of quartz, alumina, or other appropriatematerial for withstanding the operational temperatures of the reactionzone. The shells 1628 and 1630 are generally made of steel, titanium, orother appropriate materials.

The top cap assembly 1604 and the bottom cap assembly 1606 are generallymade of steel or other appropriate materials. The top cap assembly 1604and the bottom cap assembly 1606 are mounted or attached to the top andbottom, respectively, of the shells 1628 and 1630 to hold the shells1628 and 1630 in a generally concentric arrangement or relationship toeach other with a space 1634 there between. The space 1634 between theshells 1628 and 1630 defines a cooling fluid region.

A top and bottom plug, cap or insert 1636 and 1638 are disposed withinthe secondary shell 1630 near the top and bottom, respectively, of thebody 1602. The top and bottom plugs 1636 and 1638 are generally made ofsteel or other appropriate materials. The bottom plug 1638 is mounted orset within the secondary shell 1630 down against an inner surface orflange of the bottom cap assembly 1606 and engages a bottom end of thereactor tube 1632. The top plug 1636 is mounted or set within thesecondary shell 1630 near a top end of the secondary shell 1630 andengages a top end of the reactor tube 1632. The reactor tube 1632 andthe top and bottom plugs 1636 and 1638 are generally held in place byany appropriate means, e.g., such as that described above for FIG. 7.The top and bottom plugs 1636 and 1638 generally hold the reactor tube1632 in a generally concentric arrangement or relationship to thesecondary shell 1630, with a space 1640 between the reactor tube 1632and the secondary shell 1630. The space 1640 between the reactor tube1632 and the secondary shell 1630 defines a gas coolant region.

The heating element 1608 is any appropriate type described above andextends along, generally concentrically with, and parallel to, thecentral longitudinal axis of the body 1602 or the reactor tube 1632. Theheating element 1608 (at or near the top end thereof) contacts a topelectrode assembly 1642 that is mounted or attached to the body 1602 andextends through the shells 1628 and 1630 above the top plug 1636.Additionally, the heating element 1608 is mounted or attached at a topend to a tensioning assembly 1644 (e.g., a pneumatic tensioning device,a spring biasing assembly, etc.) through a hole in the top electrodeassembly 1642 and a hole in a lower portion of the top cap assembly1604. The heating element 1608 is also mounted or attached at a bottomend to a bottom electrode assembly 1646. The bottom electrode assembly1646 is mounted or attached to a lower portion 1648 of the bottom capassembly 1606 and extends through the lower portion 1648 to connect tothe heating element 1608 at a point along a longitudinal axis of thelower portion 1648, which is coaxial with the longitudinal axis of thebody 1602 or the reactor tube 1632. The heating element 1608 extendsthrough a hole in a flange 1650 of the bottom cap assembly 1606 down tothe bottom electrode assembly 1646. The heating element 1608 is held intension by the tensioning assembly 1644 acting against an upper portionof the top cap assembly 1604. Thus, when the heating element 1608 heatsup during gas processing or thermal cracking operations and cools downafterwards, any thermal expansion or contraction of the heating element1608 is compensated for by the tensioning assembly 1644, which maintainsthe heating element 1608 in tension, so that the heating element 1608remains generally concentric and parallel to the central longitudinalaxis of the body 1602 or the reactor tube 1632.

The technique described for FIG. 8 for mounting or attaching the heatingelement 1608 using the top and bottom electrodes 1642 and 1646 and thetensioning assembly 1644 is an alternative embodiment that can beapplied to the overall embodiment shown in FIG. 7, given appropriatemodifications to support this alternative structure. On the other hand,the technique described for FIG. 7 for mounting or attaching the heatingelement 1508 using the top and bottom electrodes 1546 and 1548 and thespring bias assembly 1550 is an alternative embodiment that can beapplied to the overall embodiment shown in FIG. 8, given appropriatemodifications to support this alternative structure.

An interior surface of a wall of the reactor tube 1632 defines an innervolume, all or part of which includes a longitudinal elongated reactionzone generated in the vicinity of the heating element 1608 during gasprocessing or thermal cracking operations. The reactor tube 1632 is thusthe heating or reaction chamber of the thermal cracking apparatus 1600,and the central longitudinal axis of the body 1602 or the reactor tube1632 is also considered to be a central longitudinal axis of thelongitudinal elongated reaction zone.

Electrical power is provided to the heating element 1608 through the topelectrode assembly 1642 and the bottom electrode assembly 1646 duringgas processing operations. The top electrode assembly 1642 electricallyconnects to, or near, the top of the heating element 1608. The bottomelectrode assembly 1646 electrically connects to, or near, the bottom ofthe heating element 1608.

The feedstock process gas inlet 1612 is fluidly connected to a feedstockprocess gas source (not shown). The feedstock process gas inlet 1612 isalso attached or mounted to the shells 1628 and 1630 to be in fluidcommunication with the inner volume of the reactor tube 1632 viaapertures or holes through the shells 1628 and 1630, the top plug 1636,and the reactor tube 1632. During gas processing operations, thefeedstock process gas is flowed from the source through the feedstockprocess gas inlet 1612 and into the inner volume (the reaction zone) ofthe reactor tube 1632 through a series of holes or apertures 1652 in thewall of the reactor tube 1632 near the top of the reactor tube 1632, forembodiments in which the gas flow direction is downward. Within theinner volume or the reaction zone, the feedstock process gas circulatesaround the heating element 1608, which heats the feedstock process gasin the vicinity thereof to thermally crack the feedstock process gasinto constituent elements and/or lower order molecules, i.e., thegaseous and solid products. For embodiments in which the gas flowdirection is upward, on the other hand, the feedstock process gas inlet1612 and the series of holes or apertures 1652 in the wall of thereactor tube 1632 are placed near the bottom of the reactor tube 1632.

In some embodiments, the secondary feedstock process gas inlet 1614 isfluidly connected to a source (not shown) of a second feedstock processgas having additional particles (e.g., nano-particles) floating therein.The secondary feedstock process gas inlet 1614 is attached or mountedthrough the shells 1628 and 1630 and the top plug 1636 to be in fluidcommunication with the inner volume of the reactor tube 1632 viaapertures or holes through the shells 1628 and 1630 and the top plug1636. During gas processing operations, the feedstock process gas withadditional particles is flowed from the source through the secondaryfeedstock process gas inlet 1614 into the inner volume of the reactortube 1632, i.e., the reaction zone. Within the inner volume or thereaction zone, the feedstock process gas with additional particles mixeswith the feedstock process gas from the feedstock process gas inlet1612. The additional particles (e.g., nano-particles of Silicon, siliconcarbide, etc.)

assist in the heating, and thus the thermal cracking, of the feedstockprocess gas in the reaction zone. In some embodiments, the feedstockprocess gas having additional particles and the secondary feedstockprocess gas inlet 1614 are considered optional or are not included inthe thermal cracking apparatus 1500.

The technique described for FIG. 8 for providing the feedstock processgas with additional particles through the secondary feedstock processgas inlet 1614 is an alternative embodiment that can be applied to theoverall embodiment shown in FIG. 7, given appropriate modifications tosupport this alternative structure. On the other hand, the techniquedescribed for FIG. 7 for providing the feedstock process gas withadditional particles through the secondary feedstock process gas inlet1514 is an alternative embodiment that can be applied to the overallembodiment shown in FIG. 8, given appropriate modifications to supportthis alternative structure.

In some embodiments, the cooling gas inlet and outlet 1616 and 1618 areattached or mounted to the shells 1628 and 1630 to be in fluidcommunication with the gas coolant region, i.e., the space 1640 betweenthe reactor tube 1632 and the secondary shell 1630, via apertures orholes through the shells 1628 and 1630. During gas processingoperations, a coolant gas (e.g., air, nitrogen, a noble gas, etc.) isflowed from a source thereof, through the cooling gas inlet 1616, andinto the gas coolant region (space 1640). The coolant gas thuscirculates within the gas coolant region, absorbs some of the heat fromthe reactor tube 1632 (thereby serving to cool the reactor tube 1632),and exits through the outlet 1618 to be cooled, recycled, discarded orstored.

In some other embodiments, the space 1640 between the reactor tube 1632and the secondary shell 1630 is filled with a thermally insulating orconducting material, rather than having a coolant gas flow therein. Invarious embodiments, the use or selection of the coolant gas or thethermally insulating or conducting material for the space 1640 generallydepends on the thermal requirements for the overall configuration of thethermal cracking apparatus 1600, the type of the feedstock process gas,the type or characteristics of the desired solid and/or gaseousproducts, and/or the process parameters of the gas processingoperations. Different embodiments, in other words, generally havedifferent thermal requirements.

In some embodiments, the cooling fluid inlet and outlet 1620 and 1622are attached or mounted to the outer shell 1628 to be in fluidcommunication with the cooling fluid region, i.e., the space 1634between the shells 1628 and 1630, via apertures or holes through theouter shell 1628. During gas processing operations, a coolant fluid(e.g., water, etc.) is flowed from a source thereof, through the coolingfluid inlet 1620, and into the cooling fluid region (space 1634). Thecoolant fluid thus circulates within the cooling fluid region, absorbssome of the heat from the secondary shell 1630 (thereby cooling thesecondary shell 1630), and exits through the outlet 1622 to be cooled,recycled, discarded or stored. In this manner, the action of the coolantfluid, or the combined action of the coolant fluid and the coolant gas,ensures that the outer surface of the thermal cracking apparatus 1600(i.e., of the body 1602 or the outer shell 1628) remains cool, or doesnot become too hot to pose a danger to nearby equipment or personnel.

In the illustrated embodiment, the thermal cracking apparatus 1600further includes a primary hopper 1656 and a secondary hopper 1658. (Asmentioned above for the hopper 1562, in some embodiments, differenthoppers 1656 and/or 1658 are used for different applications, so thethermal cracking apparatus 1600 is designed with an attachment mechanismfor removal and replacement of the hopper 1656 and/or 1658, so that aclean or different hopper 1656 and/or 1658 can be attached for eachapplication.) The primary hopper 1656 is mounted or attached to thelower portion 1648 of the bottom cap assembly 1606. The primary hopper1656 generally has lower and upper portions 1660 and 1662 and lower andupper filters 1664 and 1666. The lower portion 1648 of the bottom capassembly 1606 extends through the upper portion 1662 and the upperfilter 1666 down to the lower portion 1660 to provide a fluid connectionbetween the inner volume of the reactor tube 1632 and the lower portion1660. The upper filter 1666 generally separates the lower and upperportions 1660 and 1662. The lower filter 1664 is disposed at or near thebottom of the lower portion 1660 at the solid product outlet 1626. Thesolid product outlet 1626 is mounted or attached to the lower portion1660, at or near a bottom thereof. The gaseous product outlet 1624 ismounted or attached to the upper portion 1662 (at or near a sidethereof) to provide a fluid connection between the upper portion 1662and the secondary hopper 1658.

During gas processing operations, the gaseous and solid products fall orflow down from the inner volume of the reactor tube 1632, through thehole in the flange 1650, through the lower portion 1648 of the bottomcap assembly 1606, and into the lower portion 1660 of the primary hopper1656, for embodiments in which the gas flow direction is downward. Thesolid products generally continue to fall and pass out through the solidproduct outlet 1626. The desired solid product is typically the carbonnano-particles described above; however, some larger aggregateparticles, debris or flake material can also sometimes form within thereactor tube 1632 and fall down into the primary hopper 1656. The lowerfilter 1664 is generally designed or selected to be capable of catchingthese larger particles and allowing the desired solid product to passthrough to the solid product outlet 1626. The larger particles areperiodically removed from the primary hopper 1656. For embodiments inwhich the gas flow direction is upward, on the other hand, the solidproducts flow out of the reactor tube 1632 near the top thereof, unlessthe solid products are heavy enough to fall against the gas flow, inwhich case the solid product outlet can be placed near the bottom of thereactor tube 1632, similar to that described previously.

For embodiments in which the gas flow direction is downward, the gaseousproduct is generally forced to flow (in the direction of arrows 1668)down from the reactor tube 1632, into the lower portion 1660 of theprimary hopper 1656, up through the upper filter 1666, into the upperportion 1662, and out through the gaseous product outlet 1624. (Forembodiments in which the gas flow direction is upward, on the otherhand, the gaseous product is generally forced to flow out of the reactortube 1632 near the top thereof.) Some of the solid product (such as thesmaller particles) can potentially be swept up in the flow of thegaseous product, instead of falling to the bottom of the primary hopper1656 as mentioned above. The upper filter 1666 is generally designed orselected to be capable of catching these particles, which eventually areremoved with the other solid products through the solid product outlet1626. An ultrasonic port 1670 (mounted or attached to the upper portion1662) provides an ultrasonic or mechanical vibrational assist forremoving these particles by the upper filter 1666. The gaseous productis exhausted with a Venturi assist and a flow of nitrogen gas throughthe gaseous product outlet 1624 to the secondary hopper 1658. Most ofthe solid product has been removed from the gaseous product at thispoint, but some can still remain. Thus, additional gas/solid separationvia cyclone or electrical precipitation is implemented for furtherseparation at the secondary hopper 1658. The gaseous products are thenremoved by flowing through a gaseous product outlet 1672 from thesecondary hopper 1658. The gaseous product outlet 1672 is mounted orattached to the secondary hopper 1658 to provide a fluid connection tothe interior of the hopper 1658. The gaseous product outlet 1672 is alsofluidly connected to a downstream storage apparatus or further gasprocessing apparatus. The gaseous products are thus flowed out throughthe gaseous product outlet 1564 to the downstream storage apparatus orfurther gas processing apparatus.

The exhaust system technique described for FIG. 8 for exhausting andseparating the gaseous and solid products through the hoppers 1656 and1658 is an alternative embodiment that can be applied to the overallembodiment shown in FIG. 7, given appropriate modifications to supportthis alternative structure. On the other hand, the exhaust systemtechnique described for FIG. 7 for exhausting and separating the gaseousand solid products through the hopper 1562 is an alternative embodimentthat can be applied to the overall embodiment shown in FIG. 8, givenappropriate modifications to support this alternative structure.

In some situations, some of the solid products can accumulate within theinner volume of the reactor tube 1632, e.g., on the interior surface ofthe wall of the reactor tube 1632 and/or the heating element 1608. Someembodiments may also use any appropriate structures or subassemblies forforcibly removing the solid products or cleaning the reaction zone.

Reference has been made in detail to embodiments of the disclosedinvention, one or more examples of which have been illustrated in theaccompanying drawings. Each example has been provided by way ofexplanation of the present technology, not as a limitation of thepresent technology. In fact, while the specification has been describedin detail with respect to specific embodiments of the invention, it willbe appreciated that those skilled in the art, upon attaining anunderstanding of the foregoing, may readily conceive of alterations to,variations of, and equivalents to these embodiments. For instance,features illustrated or described as part of one embodiment may be usedwith another embodiment to yield a still further embodiment. Thus, it isintended that the present subject matter covers all such modificationsand variations within the scope of the appended claims and theirequivalents. These and other modifications and variations to the presentinvention may be practiced by those of ordinary skill in the art,without departing from the scope of the present invention. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention.

What is claimed is:
 1. An apparatus, comprising: a reaction zoneconfigured to receive a hydrocarbon gas; a heating element disposedwithin the reaction zone and configured to heat the hydrocarbon gas, thereaction zone configured to thermally crack the hydrocarbon gas at acracking temperature; and an output coupled to the reaction zone, theoutput configured to output a plurality of carbon aggregates generatedin response to thermally cracking the hydrocarbon gas at the crackingtemperature.
 2. The apparatus of claim 1, wherein the plurality ofcarbon aggregates has a ratio of carbon to other elements, exceptHydrogen, greater than 99.9%.
 3. The apparatus of claim 1, wherein anyone or more of the plurality of carbon aggregates has a first Raman peakat approximately 750 cm⁻¹ and a second Raman peak at approximately 1580cm⁻¹.
 4. The apparatus of claim 1, wherein any one or more of theplurality of carbon aggregates comprises one or more multi-walledspherical fullerenes.
 5. The apparatus of claim 1, wherein any one ormore of the plurality of carbon based aggregates has a dimensionapproximately between 10 microns and 500 microns.
 6. The apparatus ofclaim 1, wherein the plurality of carbon aggregates includes one or moregraphene-based layers or structures.
 7. The apparatus of claim 1,wherein the plurality of carbon aggregates has a specific surface areaapproximately between 10 m²/g and 200 m²/g.
 8. The apparatus of claim 1,further comprising a pellet formed by compression of at east some of theplurality of carbon aggregates.
 9. The apparatus of claim 1, wherein thehydrocarbon gas configured to be flowed at a rate approximately between1 slm and 10 slm.
 10. The apparatus of claim 1, wherein the crackingtemperature is approximately between 1600° C. and 2200° C.